Avaliação de índices de vegetação MODIS para detecção de desmatamentos na Amazônia

Abstract

Vegetation indices (NDVI and EVI) obtained from MODIS products (25m and 50m, surface reflectance) were evaluated in relation to the possibility of detecting and monitoring deforestation areas in Amazonia. A new vegetation index, the DNRG (Normalized Difference between Red and Green spectral bands), was proposed with the same objective. The radiometric quality of the multi-date MODIS products was evaluated to verify the possibility of using vegetation index to generate deforestation maps. The internal accuracy of multi-date composites were evaluated providing a value of positional error less than 1 pixel (< 25m) and, consequently geometric corrections were not necessary. The potential of surface reflectance MODIS products was evaluated in the region of Terra do Meio (Pará State, Brazil, between latitudes 06°00’S to 08°00’S and longitudes 51°00’W to 54°00’W), using the Euclidian minimum distance supervised algorithm of classification. Global accuracies above 87% were obtained demonstrating a good potential for using these products in systems for deforestation detection in near real time.